Earthquake

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An earthquake is a sudden and sometimes catastrophic movement of a part of the Earth's surface. Earthquakes result from the dynamic release of elastic strain energy that radiates seismic waves. Earthquakes typically result from the movement of faults, planar zones of deformation within its the upper crust. The word earthquake is also widely used to indicate the source region itself. The Earth's lithosphere is a patch work of plates in slow but constant motion (see plate tectonics). Earthquakes occur where the stress resulting from the differential motion of these plates exceeds the strength of the crust. The highest stress (and possible weakest zones) are most often found at the boundaries of the tectonic plates and hence these locations are where the majority of earthquakes occur. Events located at plate boundaries are called interplate earthquakes; the less frequent events that occur in the interior of the lithospheric plates are called intraplate earthquakes (see New Madrid Seismic Zone). Earthquakes also occur in volcanic regions and as the result of a number of anthropogenic sources, such as reservoir induced seismicity, mining and the removal or injection of fluids into the crust. Seismic waves including some strong enough to be felt by humans can also by caused by explosions (chemical or nuclear), landslides, and collapse of old mine shafts though these sources are not strictly earthquakes.

Related Topics:
Earth - Seismic wave - Fault - Crust - Lithosphere - Plate tectonics - Stress - Tectonic plates - Interplate earthquake - Intraplate earthquake - New Madrid Seismic Zone - Volcanic - Humans

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